major revelation this morning from michael douglas, telling "the guardian" newspaper that the cause of his cancer was not smoking of drinking but a sexually transmitted disease, the hpv virus. This is front page news everywhere this morning. Was the announcement a surprise to you? It wasn't. As we're learning more about mouth and throat cancers, many of tease are caused by hpv, the human papiloma virus. It's picked up in oral sex. These are on the rise. What is hpv? It stands for human papilloma virus. It can cause warts. We have focussed in the last few years, on cervical cancer in women. It's preventable. Research said this morning nearly every sexually active american are be exposed to at least one type of virus in his or her lifetime. How does one prevent getting hpv? A vaccine can prevent cancer. We've been vaccinating young girls against hpv for years. Now we vaccinate young boys. You need to vaccinate people before they pick it up. It has to happen in the teen s, before kids are sexually active. We think it with prevent cervical and throat cancer. It makes people nervous, this vaccine. I'm a parent. Parents don't want to think about their kids eventually becoming sexually active. Everyone will be eventually. This can prevent a cancer. The you get this type of throat cancer, it's more treatable. Less likely to spread. Than a smoking caused one. Right. Brave to clarify from michael douglas. Very. Coming up, former

This transcript has been automatically generated and may not be 100% accurate.